Fault-Tolerant Control Method for Active Steering Control of Rail Vehicles Based on Overdrive Characteristics

Active steering control significantly improves the curving performance of rail vehicles. However, failures can occur in any part of the active control system. As failure in an actuator can directly affect the running attitude of the bogie, fault-tolerant control for such failures is particularly important. In this study, a fault-tolerant control method is proposed based on the classical active steering control structure, where each axle is equipped with two actuators. First, the optimal yaw angles of the wheelset under constraints are obtained in the control layer; then, the performance index reflecting the allocation and actual implementation effects is introduced in the allocation layer. Subsequently, the fault-tolerant control effect is analyzed for four typical fault cases: self-lock, back to zero, cutoff, and abnormal action. The results show that compared to the traditional geometric control method, the fault-tolerant control method not only maintains the steering control effect under fault cases but also ensures the running safety of the bogie after an actuator failure. Next, the weights of the cost functions in the allocation layer are analyzed; it is recommended that the weight for allocation effect should not be smaller than 0.1, as it can affect the redistribution transition process. Finally, it is proved that the controller has good parametric robustness. The results can be used as a reference for fault-tolerant control of active steering systems.